REVENUES - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of revenue:
Total revenues	$ 225,310	$ 116,588	$ 596,677	$ 449,665
Oilfield services transferred at a point in time
Disaggregation of revenue:
Total revenues	0	0	0	0
Oilfield services transferred over time
Disaggregation of revenue:
Total revenues	$ 225,310	$ 116,588	$ 596,677	$ 449,665